This invention relates to a method of producing steel slabs. More particularly, it relates to such a method in which the slabs are rolled from a bottle-cap mold ingot.
Slabs of steel are ordered on the basis of metallurgical grade, maximum weight, and specified width. According to the metallurgical grade, the steel is poured either into a bottle-cap ingot mold, which is characterized by a fixed volume, or into either an open-top or a hot-top ingot mold, which has a variable volume.
In the past, bottle-cap ingots were somewhat arbitrarily assigned a maximum providing yield of 96% when rolled into slabs of various widths. This percentage was based upon the maximum yield from the highest yielding ingot size. Thus, to determine the proper size ingot mold for a particular slab, a data base was first searched to obtain the smallest bottle-cap ingot mold in stock that would product as ingot: (1) having one cross-sectional dimension larger than the sum of said specified width plus the width increment reserved for edge work, and (2) a full mold ingot weight greater than the ordered maximum slab weight.
The ordered maximum slab weight was then divided by the maximum providing yield to obtain the required ingot weight. If this weight was about the same as the full mold ingot weight of the ingot mold selected from the data base, this mold was used. If not, the next larger ingot mold was selected.
It has been found that the yield from a bottle-cap ingot varies as much as 8%, depending upon the size of the ingot and the width of the slab. Thus, if ingot sizes other than the highest yielding ingot size were used, the resultant slab was sometimes lighter than the desired weight.
It is an object of the present invention to provide a method of producing a slab of steel from a bottle-cap ingot in which the actual weight of the slab is about equal to the ordered maximum weight of the slab.